(1) Technical Field
This invention pertains to catcher subs connected in well flow conduits in which a ball seals to permit pressurization of fluid in the conduit above the ball. The invention especially pertains to a catcher sub from which the ball is expended only after pressure in the conduit is increased and later reduced.
(2) Background Information
A number of catcher subs are available for use in well conduits which permit pressurization of fluid in the conduit to operate pressure operated well tools in the conduit above the catcher sub. Very high fluid pressures, often in excess of 5,000 psi, are required to operate the pressure operated well tools and often pressures in excess of the very high operating well tool operating pressures are required to shear pins and expend a sealing ball and seat downwardly from the catcher sub. When pins are sheared by high well conduit pressures, a pressure shock wave is released to travel downwardly in the conduit from the catcher sub into open producing formations below, probably causing damage to the formations which will require expense and time to repair.